TM 5-6115-593-12 TO 35C2-3-463-1 proportional  to  their  product.    Power factor,   the   ratio   of   actual   power   to apparent     power,     is     measured     by POWER FACTOR meter M110. e. Preheat System.  To facilitate cold weather starting,    a    means    is    provided    whereby engine temperature may be maintained at a predetermined  value.    To  achieve  this,  two electrical  heating  coils  are  immersed  in  the engine   coolant   and   one   heating   element located  in  the  engine  oil.    Constant  coolant temperature  is  maintained  by  thermostatic switch  S301  in  series  with  relay  K109,  the contacts  of  which  are  in  series  with  H101, H102 and H103. PREHEAT SYSTEM switch S105 controls the application of external AC power  to  relay  K107  (engine  run  relay  K1 contacts  1  and  2  inhibit  this  function  when the  engine  is  running).    The  contactors  of K107,   in   turn,   control   the   application   of external AC power to the preheat system. f. Battery    Charger.        Battery    Charger    BC1 maintains the generator set starting batteries  at  full  charge.    The  source  of  AC power for BC 1 is either external or from the generator.        Relays    K108A    and    K108B ensure  that  BC1  receives  power  from  only one   of   the   sources   or   that   the   external source  will  be  used  when  both  options  are available. 1-16.  LUBE  OIL  SYSTEM.    Lubricating  oil  is  used  to reduce   wear   and   overheating   due   to   friction   and   to enable close tolerances and ease of movement between engine parts moving adjacent to each other.  The engine is   pressure   lubricated,   pressure   being   supplied   by   .a gear-type,  self-regulating  pump  mounted  inside  the  oil pan and mechanically coupled to the engine crankshaft. Because   overheated   oil   loses   some   of   its   lubricating properties, the oil, prior to being filtered is fed to an oil cooler located on the right-hand side of the engine.  The oil   is   then   filtered   by   three   full-flow   filters   which   are mounted  just  below  the  oil  cooler.    The  filtered  oil  is supplied  to  the  engine's  main  oil  header  and  moving parts.    Oil  pressure  gauges  are  connected  at  the  input and output sides of the fuel filter assembly to ensure its proper operation.  As insurance against the interruption of   this   flow   by   a   dirty   or   clogged   line,   an   automatic bypass   valve   is   mounted   in   the   filter   assembly.   In addition to the oil level dipstick, an oil level sight gauge provides  the  operator  with  a  visual  readout  of  the  lube oil  level  while  the  engine  is  running.    Oil  pressure  is monitored  by  a  meter  located  on  the  Engine  Control Panel. 1-17.  COOLING SYSTEM.  The purpose of the engine cooling system is to remove excessive heat created by normal  engine  operation.    To  accomplish  this,  a  liquid coolant  is  circulated  through  liners  located  around  the engine    cylinders,    cylinder    heads,    and    fuel    injector sleeves.      The   coolant,   driven   by   an   engine-mounted centrifugal pump, removes the heat generated at these points and carries it to the radiator assembly where it is dissipated by air forced into motion by an electric motor B102   (powered   by   main   generator   G1)   and   a   fan. Optimum engine operating temperature is obtained by a thermostatic control valve which regulates coolant flow. In order to keep the engine warm in preparation for cold- weather    starting,    the    coolant    water    is    electrically preheated  and  circulated  throughout  the  engine  by  the preheat  system.    A  small  amount  of  coolant  from  the main  channel  is  passed  through  a  combination  filtering and treating assembly which acts to inhibit the formation of rust.  During severe cold weather conditions (with the housing  kit  installed),  the  radiator  louvers  are  indirectly controlled by coolant temperature. As coolant temperature  drops,  the  louver  doors  are  automatically moved   toward   the   closed   position   by   a   hydraulically operated actuator. 1-18.  FUEL   SYSTEM.      (See   figure   1-8.)   The   prime purpose  of  the  fuel  system  is  to  bring  the  fuel  (under pressure)  from  a  point  of  temporary  storage  (the  day tank)  to  the  point  of  final  use  -the  engine's  combustion chamber.  A second and equally important function is to regulate   engine   speed   by   controlling   the   rate   of   fuel consumption.    A  fuel  injection  pump  at  the  side  of  the engine takes fuel from the day, or 1-30